Resealable plastic dispensing closure members or, simply, closures are principally applied to cap or close containers for beverages, liquid soaps and other liquid and fluent material that one may purchase at the supermarket for household use or otherwise. Fastened or otherwise attached to a bottle, vessel, or container, as variously termed, the closure allows the container to be opened, a portion of the contents to be poured out, and then resealed for later occasions on which to dispense remaining portions. Such closures also find application in different fields, as example, as a cap to a drinking container, such as a baby training cup or a cyclist's water bottle, wherein to dispense the beverage the closure's dispensing spout is inserted directly into the users mouth.
In U.S. Pat. No. 4,440,327 to Dark, the present inventor, granted Apr. 3, 1984, entitled "Fluid Dispensing Closure with Integral Valve", "the Dark patent", one closure is described that contains a swivelable spout and an invertible elastic membrane or diaphragm with the entire closure being formed in one piece of plastic material by an injection molding process. The spout is hingedly connected to the closure base along one side of the spout's foot end or base, permitting pivotal movement of the spout between a dispensing position and a closed or sealed position. Another portion of that spout's bottom end is coupled to the diaphragm, while the remaining portion of the diaphragm's periphery is connected to the closure base. The diaphragm seals the front or dispensing end of the spout from the spout's bottom end located on the inner side of the closure. Fluid may thus pass from the closure only through the passage in the spout.
Swiveling the spout about its pivot thus also moves or swivels the invertible diaphragm. Swinging the spout from an upright dispensing position to a down closed position, a portion of the diaphragm is thus swung by the spout during which movement the diaphragm's shape changes from a generally convex shape, which is resiliently flexed or deformed as the diaphragm is carried through a bi-sector plane defining a dead center position, and is elastically restored to a relatively concave shape when the spout is in the closed position. The invertible diaphragm's convex shape provides a force tending to hold the spout in its dispensing position and the concave shape provides a force tending to hold the spout closed. With the spout in the closed position a resilient seal located at the bottom of the spout engages and seals to a seal surface on the closure base to seal the closure.
Effectively the invertible diaphragm pre-loaded the spout in each position, open or closed, in which the user set the spout. The preferred embodiment of that prior closure invention made full use of the pre-load feature by incorporating only the invertible characteristic in the diaphragm. Closure structures built in accordance with the teachings of the Dark patent established the viability of a one piece closure that could be flipped open and closed.
Such closure design proved versatile; closures could be fabricated in various sizes, both large and small. So effective was the invertible diaphragm principle that in small sized closures it was found that the spout was more difficult than desired to flip open. The size and shape of the diaphragm governed the effort required of the user to open and close the closure. During pivoting of the spout, the diaphragm is temporarily distorted in shape in order to pass through the bi-sector plane, dead center. The percentage of the diaphragm's length that must be temporarily deformed, thusly, depends on the shape of the diaphragm. The greater the percentage of distortion of the diaphragm that is required, the greater the effort required to flex it. As example, a long diaphragm with a shallow angle relative to the dead center bi-sector plane, the percentage deformation was 14%, whereas with a short diaphragm with a greater angle the percentage was 20%. All other physical characteristics being equal, the force that the user must exert to open the latter closure is greater.
One ready way to reduce the effort required to operate the closure is by using a softer and more pliable plastic material for its construction. While that may be an acceptable solution for many applications, so doing sometimes works against the total closure system. A closure of softer plastic while easier to flex, is also more easily distorted in the process of screwing the closure onto the associated bottle. Such distortion may cause the spout to come unlatched, resulting in leakage.
As hereinafter brought out, one aspect of the present invention addresses curing that difficulty without resort to substitution of a softer plastic material. With the invention stiffer plastics may be used with less likelihood of distortion and without requiring excessive force to operate the closure. An object of the present invention is to provide an improved diaphragm for the closure, one that is compact, but which, nonetheless retains the invertible diaphragm structure, and does not require as much force to raise the spout, thereby allowing the closure to be opened and closed more easily.
In a preferred form of the closure described in the Dark patent, a latch is provided to hold the spout closed. The front end of the spout could be latched against a sturdy wall of the closure base, creating an axially directed compressive force on the spout that served to further compress the seal at the bottom end of the spout, enhancing sealing action. With outward flared seals, such as those in the shape of a Belleville spring, compressive forces created within the container to which the closure is attached, such as may be caused by vaporization of confined fluids, serve to further tighten the seal.
In practical application it was also discovered that latching the spout at the front end as suggested in the Dark patent was not always effective. In those applications in which the particular closure was fitted to containers by screw threads molded onto the closures inner surface in which the closure is adapted to be screwed onto a threaded bottle opening, the front latch would sometimes release and allow leakage. The closure in that application is placed on a threaded bottle top and is then twisted by automatic assembly machinery to screw the closure fully into place until the closure could be turned no more. However, the turning force, sometimes was not released quickly enough, and was sometimes great enough to cause overtightening and temporary distortion of the closure. Overtightening of the plastic closure was found to temporarily distort its geometry, thereby causing the front latch to release. Since the bottle being capped was filled with liquid, with the spout unlatched some leakage could thereafter occur, an obviously undesirable consequence.
To cure that latching problem Komischke, in U.S. Pat. No. 4,860,934 granted Aug. 29, 1989, entitled, Closure for Receptacles, assigned to the Schmalbach-Lubeca AG company, a licensee, provides a pair of side latches to hold the spout in the closed position, one located on each side of the pivotally mounted dispensing spout.
In general each such side latch includes an upstanding elastic post or web located to the side of the spout containing a laterally extending protrusion or bar, as variously termed, and the adjacent side of the pivotable spout contains a latch rib or strip. The bar lies in the path of travel of the spout rib, wherein the web's bar and the rib inter-engage to thereby form a releasible latch. When the spout is pivoted from the upright dispensing position toward the closed position, the rib first encounters and abuts against the bar, requiring the user to exert a greater force on the spout and thereby force the upstanding web, through force exerted on the rigid latch bar, to temporarily bend, flex outwardly to the side, away from the spout, allowing the rib to be moved past the bar and the spout to attain its closed position. Due to its elasticity the web snaps back to its normal upright position with the bar overlying and in blocking contact with the corresponding rib on the spout in latching engagement, latching the spout in the closed position, and thereby prevents the spout from prematurely opening. All such latches are released by the user applying suitable force to uplift the spout. More exact details may be found in the Komischke patent. Such side latches are preferably used in conjunction with the front latch, such as disclosed in my prior patent, U.S. Pat. No. 4,440,327.
The twisting force used to screw the closure member onto the bottle as earlier described might sometimes cause one side latch to temporarily release, the other side latch, nonetheless, remained active and held. Hence the pivotable spout remains in the closed position and, upon removal of the twisting force, the one side latch restores to its position latching the spout, joining with the continuing latching function of the other side latch, as the temporarily deformed plastic closure elastically restores to its proper shape under the action of the stored elastic force. Though offering a solution to the described problem, as is evident from review of the Komischke patent, the tooling to manufacture the closure is more difficult and complex.
The latch mechanism illustrated in the Komischke patent can only be molded as an undercut in the stationary half of the mold. To make a mold capable of producing such undercut shape requires inclusion of retractable core pins in the stationary half of the mold. During molding those core pins must be retracted out of the mold cavity before the mold opens. In this manner the undercut portion can be laterally flexed out of its position in the cavity steel. More specifically, the upstanding wall on which the latch protrusion is molded is required to flex as the mold is moved, allowing the protrusion to exist the undercut in the mold in which the protrusion was formed. The upstanding wall can only flex, however, if there is a hollow area behind that wall. Such hollow area is formed by the retractable core pins in the stationary half of the mold. The pins are retracted before the mold opens, as previously described, vacating the necessary space to create the hollow area.
One approach heretofore taken by the present inventor to avoid expensive tooling containing supplementary moveable rods of the type needed for the side latch disclosed in Komischke was to carefully shape the geometry of the latch member bar and associated web so that the supporting web was tapered, wider at the bottom than at the top, and the protruding bar was also tapered. That allowed the protrusion to be resiliently bent over into the portion of the cavity in the tool vacated by the web portion as the tooling cavity was withdrawn. Though use of the foregoing method was generally successful, in many instances the protrusions were damaged in that process, resulting in a smaller than desired yield of acceptable closures in the manufacturing process and, hence, less favorable manufacturing costs. An additional object of the invention is to provide a new side latch design for the one piece closure that does not damage the latch during manufacture, achieving higher yields in the manufacturing process, and to the new method of manufacture.
The invention also provides a novel design for the structure of side latches in a one piece plastic closure member and an associated novel method of manufacture for those members. The invention permits manufacture of one piece closures containing side latches with better manufacturing yields and, hence, at lower manufacturing cost than heretofore; a decided practical advantage.
Closures are used to cap threaded bottles. With closures of type shown in the Dark patent, the diaphragm and the supporting structure may be designed to fit above the top of the bottle and/or may be designed to fit within the neck of the bottle. Often a particular closure design is achieved to obtain desired physical characteristics, a feel, for a particular spout and diaphragm, such as size and particular ease of operation, that heretofore could be achieved only if as a consequence the diaphragm was required to extend within the neck of the bottle. Ordinarily that should not pose an obstacle as one should ordinarily expect the inner diameter of the bottle to be specified to appropriate tolerance.
Unfortunately the bottle manufacturing industry allows a wide tolerance on the "I" dimension, the inside dimension of the bottle's neck, and many vary considerably in size. If the diaphragm were to be so large in size as to telescope down inside the neck of the bottle, it may not always fit and may interfere with the inside surface of the bottle's neck, an obviously undesirable situation.
The present invention addresses the need for a small size closure of the basic type disclosed in the Dark patent that is intended for application to screw type bottles in which the geometry is such that the closure's diaphragm and associated closure structure supporting such diaphragm does not descend into the bottles neck and yet the closure overall presents the desired feel of easy operation.
A related object is to provide a one piece plastic closure that uses a diaphragm that is shorter in length. An advantage to the shorter design is that it allows a dispensing cap to be designed with the diaphragm located above the bottle cap's top without causing the cap to be too tall. An ancillary benefit is that the bottle top may be sealed by a thin tamper indicating film or seal, in which the closure is screwed over the tamper seal. Hence the purchaser of that beverage is required to determine whether tampering has occurred by unscrewing the closure and breaking the seal prior to replacing the closure and consuming the bottles contents.
Reference is made to the prior Dark U.S. Pat. No. 4,440,327, granted Apr. 3, 1984, entitled "Fluid Dispensing Closure with integral Valve", the contents of which are incorporated herewithin in its entirety to describe the structure, geometry and formation of the basic closure, the mechanisms of operation, and the variety of shapes in which the invertible diaphragm for such closures may be formed as desired.
Reference is also made to the contents of the Komischke U.S. Pat. No. 4,860,934 granted Aug. 29, 1989 for a Closure for Receptacles, assigned to the Schmalbach-Lubeca AG company, including the drawings, which is incorporated herein in its entirety by reference to show the additional configurations of the closure of the kind described in my prior patent U.S. Pat. No. 4,440,327 and of the structure for incorporating side latches.